The way in which the antithesis is constituted in this ethical realm is such that self-consciousness has not yet received its due as a particular individuality. There it has the value, on the one hand, merely of the universal will, and on the other, of consanguinity. This particular individual counts only as a shadowy unreality. As yet, no deed has been committed; but the deed is the actual self. It disturbs the peaceful organization and movement of the ethical world. What there appears as order and harmony of its two essences, each of which authenticates and completes the other, becomes through the deed a transition of opposites in which each proves itself to be the nonreality, rather than the authentication, of itself and the other. It becomes the negative movement, or the eternal necessity, of a dreadful fate which engulfs in the abyss of its single nature divine and human law alike, as well as the two self-consciousnesses in which these powers have their existence-and for us passes over into the absolute being-for-self of the purely individual self-consciousness.

In this arrogance which fancies it has, by the gift of a meal, acquired the self of another's 'I' and thereby gained for itself the submission of that other's inmost being, it overlooks the inner rebellion of the other; it overlooks the fact that all restraints have been cast off, overlooks this state of sheer disruption in which, the self-identity of being-for-self having become divided against itself, all identity, all existence, is disrupted, and in which the sentiment and view-point of the benefactor suffer most distortion. It stands on the very edge of this innermost abyss, of this bottomless depth, in which all stability and Substance have vanished; and in this depth it sees nothing but a common thing, a plaything of its whims, an accident of its caprice. Its Spirit is a subjective opinion wholly devoid of essentiality, a superficiality from which Spirit has fled.

Thus possibility seems greater and greater to the self; more and more it becomes possible because nothing becomes actual. Eventually everything seems possible, but this is exactly the point at which the abyss swallows up the self. It takes time for each little possibility to become actuality. Eventually, however, the time that should be used for actuality grows shorter and shorter; everything becomes more and more momentary. Possibility becomes more and more intensive—but in the sense of possibility, not in the sense of actuality, for the intensive in the sense of actuality means to actualize some of what is possible.

Søren Kierkegaard, The Sickness Unto Death (1849), C. The Forms of This Sickness (Despair)

Whoever fights with monsters should see to it that he does not become one himself. And when you stare for a long time into an abyss, the abyss stares back into you.